1. Field of the Invention
The invention relates to a process for the production of 5-chloroxindole of the formula: ##STR6## starting from chloronitrobenzene.
2. Background Art
To date several processes for the production of 5-chloroxindole are known. For example, U.S. Pat. No. 4,761,485 describes a process for the production of 5-chloroxindole starting from 5-chloroindole. In this case, 5-chloroindole is first converted by pyridinebromide perbromide into 3,3-dibromo-5-chloroxindole, which is then converted into 5-chloroxindole by catalytic hydrogenation with palladium on carbon. Drawbacks of this process are that feedstock (5-chloroindole) is difficult to obtain and that the 5-chloroindole is obtained in poor yield.
Also, U.S. Pat. No. 4,730,004 describes a process for the production of 5-chloroxindole starting from 5-chloroisatin, whereby the latter is first converted with hydrazine hydrate into the 5 -chloro-3-hydrazon-2-oxoindole, which is then reacted by sodium methanolate into 5-chloroxindole. This process also has the drawbacks that the feedstock 5-chloroisatin is difficult to obtain and that the desired product is obtained in poor yield.